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Mechanical Polishing Effects Toward Surface Domain Evolution in Pb(Zn 1/3 Nb 2/3 )O 3 –PbTiO 3 Single Crystals
Author(s) -
Wong Meng Fei,
Zeng Kaiyang
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.04204.x
Subject(s) - polishing , nanoindentation , materials science , lapping , piezoresponse force microscopy , surface layer , crystallography , crystal (programming language) , diffraction , surface roughness , layer (electronics) , composite material , optics , ferroelectricity , chemistry , physics , optoelectronics , computer science , dielectric , programming language
This paper presents the mechanical polishing effects on the surface domains and crystal structures of relaxor‐based Pb(Zn 1/3 Nb 2/3 )O 3 –PbTiO 3 (PZN–PT) single crystals. In normal sample preparation processes, a “surface deformed layer” composed of distorted crystal structures is produced due to intense compression caused by several polishing steps using a series of lapping films down to 1 μm in particle size. This “surface deformed layer” may contribute to dissimilar properties compared with those of the interior, and also result in pop‐in events in the load–displacement curve ( P–h curve) during nanoindentation. An anomaly in the X‐ray diffraction (XRD) profiles is also found, demonstrating a broad minor peak besides the major peak in the intensity. In addition, Piezoresponse Force Microscopy reveals that the domain structures on the crystal surface appear to be distorted and aligned along the polishing direction. Therefore, a controlled fine polishing procedure using Al 2 O 3 slurry of 0.3 μm particle size is adopted to remove this “surface deformed layer.” After polishing to mirror finish, the macroscopic orientations of the domain walls agree well with the permissible domain wall directions. The topography is also altered analogous with the polarization direction. More specifically, the upward domains constitute a depression of ∼10 nm compared with the downward domains, suggesting a different hardness for the head and tail domain sections. Furthermore, the minor peak in the XRD and the pop‐in event in the nanoindentation P–h curve are successfully eliminated after this fine polishing procedure. The removal of the surface layer may also lower the coercive field of the crystals, thus enabling ferroelectric control with a smaller voltage.